Get a good conductor. For the example we can use a copper wire and a piece of copper plating. Also you will need a co-axial cable (75 ohm is better than 50 ohm, for Wi-Fi 50 ohm is better than 75 ohm).

Work out the length you need the wire to be. This is done by using the frequency value from step 1 to find the wavelength of the signal. To do this you simply need to divide the speed of light (c = 299 792 458 m/s) by the frequency (f). In the case of 2.45GHz the wavelength is 12.236 centimeter (4.8 in). Usually monopole antennas are quarter-wavelength structures, so the length of the wire should be 12.236/4 = 3.0509cm

Push the cable through so that the start of outer insulation is flush with the hole. The ground conductor is now above the ground-plane. Fold the ground conductor back and solder it to the copper ground plane.